Aircraft navigation systems frequently use velocity information calculated by different sensors onboard an aircraft to provide a navigation solution representing the location and attitude of the aircraft. For example, global positioning systems (GPS) are common sources of velocity measurements used in providing a navigation solution. Other sources of velocity measurements include measurements from an aircraft's inertial navigation system and airspeed measurements from observations of relative air pressure through a pitot tube. However, these different sources of velocity measurements are subject to different errors that increase the challenge of gathering reliable measurements of ground speed. In certain situations, a GPS may be easily jammed, causing the aircraft to rely on other less reliable sources of velocity measurement. For example, measurements from an inertial navigation system slowly drift over time and airspeed measurements via a pitot tube fail to provide accurate information about an aircraft's ground speed.
Further, in certain embodiments, a Doppler beam sharpened radar altimeter may use Doppler filters to form the Doppler beams. However, the bandwidth and power needed to form the different Doppler filters is based on the maximum speed of the aircraft. Because, the bandwidth of the Doppler filters are based on the maximum speed, the Doppler filters consume unnecessary power and resources.